Allow usage of local value symbol merged with type-only import (microsoft#47642)

Author: andrewbranch

Diff for: src/compiler/checker.ts

@@ -2235,29 +2235,23 @@ namespace ts {
                         error(errorLocation, Diagnostics.Parameter_0_cannot_reference_identifier_1_declared_after_it, declarationNameToString(associatedDeclarationForContainingInitializerOrBindingName.name), declarationNameToString(errorLocation as Identifier));
                     }
                 }
-                if (result && errorLocation && meaning & SymbolFlags.Value && result.flags & SymbolFlags.Alias) {
-                    checkSymbolUsageInExpressionContext(result, name, errorLocation);
+                if (result && errorLocation && meaning & SymbolFlags.Value && result.flags & SymbolFlags.Alias && !(result.flags & SymbolFlags.Value) && !isValidTypeOnlyAliasUseSite(errorLocation)) {
+                    const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(result);
+                    if (typeOnlyDeclaration) {
+                        const message = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier
+                            ? Diagnostics._0_cannot_be_used_as_a_value_because_it_was_exported_using_export_type
+                            : Diagnostics._0_cannot_be_used_as_a_value_because_it_was_imported_using_import_type;
+                        const unescapedName = unescapeLeadingUnderscores(name);
+                        addTypeOnlyDeclarationRelatedInfo(
+                            error(errorLocation, message, unescapedName),
+                            typeOnlyDeclaration,
+                            unescapedName);
+                    }
                 }
             }
             return result;
         }
 
-        function checkSymbolUsageInExpressionContext(symbol: Symbol, name: __String, useSite: Node) {
-            if (!isValidTypeOnlyAliasUseSite(useSite)) {
-                const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(symbol);
-                if (typeOnlyDeclaration) {
-                    const message = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier
-                        ? Diagnostics._0_cannot_be_used_as_a_value_because_it_was_exported_using_export_type
-                        : Diagnostics._0_cannot_be_used_as_a_value_because_it_was_imported_using_import_type;
-                    const unescapedName = unescapeLeadingUnderscores(name);
-                    addTypeOnlyDeclarationRelatedInfo(
-                        error(useSite, message, unescapedName),
-                        typeOnlyDeclaration,
-                        unescapedName);
-                }
-            }
-        }
-
         function addTypeOnlyDeclarationRelatedInfo(diagnostic: Diagnostic, typeOnlyDeclaration: TypeOnlyCompatibleAliasDeclaration | undefined, unescapedName: string) {
             if (!typeOnlyDeclaration) return diagnostic;
             return addRelatedInfo(

Diff for: tests/baselines/reference/mergedWithLocalValue.js

@@ -0,0 +1,19 @@
+//// [tests/cases/conformance/externalModules/typeOnly/mergedWithLocalValue.ts] ////
+
+//// [a.ts]
+export type A = "a";
+
+//// [b.ts]
+import type { A } from "./a";
+const A: A = "a";
+A.toUpperCase();
+
+
+//// [a.js]
+"use strict";
+exports.__esModule = true;
+//// [b.js]
+"use strict";
+exports.__esModule = true;
+var A = "a";
+A.toUpperCase();

Diff for: tests/baselines/reference/mergedWithLocalValue.symbols

@@ -0,0 +1,17 @@
+=== tests/cases/conformance/externalModules/typeOnly/a.ts ===
+export type A = "a";
+>A : Symbol(A, Decl(a.ts, 0, 0))
+
+=== tests/cases/conformance/externalModules/typeOnly/b.ts ===
+import type { A } from "./a";
+>A : Symbol(A, Decl(b.ts, 0, 13), Decl(b.ts, 1, 5))
+
+const A: A = "a";
+>A : Symbol(A, Decl(b.ts, 0, 13), Decl(b.ts, 1, 5))
+>A : Symbol(A, Decl(b.ts, 0, 13), Decl(b.ts, 1, 5))
+
+A.toUpperCase();
+>A.toUpperCase : Symbol(String.toUpperCase, Decl(lib.es5.d.ts, --, --))
+>A : Symbol(A, Decl(b.ts, 0, 13), Decl(b.ts, 1, 5))
+>toUpperCase : Symbol(String.toUpperCase, Decl(lib.es5.d.ts, --, --))
+

Diff for: tests/baselines/reference/mergedWithLocalValue.types

@@ -0,0 +1,18 @@
+=== tests/cases/conformance/externalModules/typeOnly/a.ts ===
+export type A = "a";
+>A : "a"
+
+=== tests/cases/conformance/externalModules/typeOnly/b.ts ===
+import type { A } from "./a";
+>A : "a"
+
+const A: A = "a";
+>A : "a"
+>"a" : "a"
+
+A.toUpperCase();
+>A.toUpperCase() : string
+>A.toUpperCase : () => string
+>A : "a"
+>toUpperCase : () => string
+

Diff for: tests/cases/conformance/externalModules/typeOnly/mergedWithLocalValue.ts

@@ -0,0 +1,7 @@
+// @Filename: a.ts
+export type A = "a";
+
+// @Filename: b.ts
+import type { A } from "./a";
+const A: A = "a";
+A.toUpperCase();